A Mondeo rear system, VAG Polo/Golf centre silencer and a pipe reducer - all from ebay.
Cut the pipework to suit dimensions taken from the car with the pipe positions drawn on the garage floor. The Mondeo silencer was not needed. There's plenty of room under the back bumber for the VAG silencer although it is longer than the original. The existing pipe upstream of the diff was still in decent condition so I cut the old system here.
I butt welded the sections together, added the three hangers cut from the old silencer and sprayed with silver stove paint.
The new system was joined to the old with a sleeve and 'U' clamp using the reducer - The original pipe is 38mm and the Mondeo pipe is 47mm.
Not as quiet as the original due to the VAG silencer being of the "straight through" design, but a reasonably mellow sound and well worth a couple of afternoons in the garage.